Water-rheostat.



PATENTED AUG. 15, 1905.

W. D. POMERUY. WATER RHEOSTAT.

APPLICATION FILED DBO. 1, 190a.

Aitorney.

[n v ntor M'IIiam fl Pomeroy Witnesses UNITED STATES PATENT OFFICE.

WILLIAM D. POMEROY, OF NORWOOD, OHIO, ASSIGNOR, BY MESNE ASSIGNMENTS, TOTHE BULLOCK ELECTRIC COMPANY, A CORPO- RATION OF OHIO.

WATER-RHEOSTAT.

Specification of Letters Patent.

Patented Aug. 15, 1905.

Application filed December 1, 1903. Serial No. 183,319.

To all whom, it may concern:

Be itknown that I, IVILLIAM D. PoMERoY, a citizen of the United States,residing at N orwood, in the county of Hamilton and State of Ohio, haveinvented certain new and useful Improvements in VVater-Rheostats, ofwhich the following is a full, clear, and exact specificationr Myinvention relates to water-rheostats, and although the sameis capable ofbeing used generally it is particularly applicable in connection withstarting motors, and especially induction-motors.

WVhere currents of very large amperage are to be regulated or where aheavy load is to be placed upon a generator, such as is necessary intesting-machines, the water-rheostat presents many advantages. A smallrheostat is capable of carrying very heavy currents, and where the wateris continually changed, as when cold water is supplied to the bottom ofthe rheostat and the heated water passed ofl? through an outlet at thetop, a large amount of energy may be absorbed. Also the resistance iscapable of being closely regulated by varying the depth of the plates inthe water, and by adding salt to the water its resistance can begraduated from the very high resistance of pure water to a comparativelylow resistance.

The object of my invention is to produce a rheostat very simple inconstruction, compact in form, and capable of gradual and rapid changein resistance. By my invention I use a tank in box form and mount theconductingplates on the hinged cover. When the cover is open, no circuitis made; but by closing the cover the circuit is closed and theresistance gradually reduced. I also provide connections, so that whenthe cover is closed the rheostat is short-circuited and directconnection made between the terminals.

The details of my invention will be understood from the followingdescription and accompanying drawings, and the novelty thereof will bemore definitely set forth in the claims.

Figure 1 is a plan view of my improved rheostat. Fig. 2 is a front viewthereof.

Fig. 3 is a sectional view on line 3 3 of Fig.

1, and Fig. .L is a sectional view on line 4 4: of Fig. 2.

The rheostat is made up in the form of a rectangular box having the ends1, sides 2, and bottom 3 of sheet-iron, the edges being bent over andriveted and all the joints carefully soldered. The cover 4, made ofwood, is hinged to the back of the box by hinges 5, which are riveted tothe back side and secured to the cover by stove-bolts 6. Secured to theunder side of the cover are conductingplates 7, three being shown inthis instance. These are made of sheet-steel triangular in outline andhave an edge 8 bent at right angles. Between each plate and the woodencover is a rolled-copper contact-strip 9, and both of these parts aresecured to the cover by several stove-bolts 10. Near the back edge ofthe cover and on the outside thereof are terminal lugs '11, which areconnected with the conducting-plates 7 and strips 9 by studbolts 12, thestud being made of copper to secure good conductivity.

Upon the front of the rheostat is mounted a copper strip 13, andextending upward therefrom are the spring-fingers 14, made of hardrolled brass and having the tips 15. The fingers and copper strip 13 aresecured to the front of the rheostat by the machine-screws 16. Thestrips 9 have the front ends 17 bent over, as shown, so that when thecover is closed they contact with the tips 15. The cover is providedwith the handle 18 to open and close the same, and, if desired, acounterbalancing-weight may be connected to the cover, so that thelatter may remain in any position placed. Extending across the rheostatare the stiffening-plates 19, of sheet-iron, having the front and backedges bent at right angles and riveted to the sides of the rheostat. Theplates 19 do not extend the full depth of the rheostat, open spaces 20being left at top and bottom.

The outside leads are connected to the terminals 11, and when the coveris wide open no circuit is made. Upon closing the cover the lower tipsof plate 7 will first contact with the water and the circuit betweenterminals 11 will be closed through the plates and water,

which will offer a high resistance. As the cover is gradually closed theplates are submerged more and more, and owing to the triangular outlineof the plates the resistance is reduced very rapidly. IV hen the coveris finally closed, the ends 17 of the strips 9 contact with the tips ofthe fingers l t, and there is then a direct connection from theterminals 11, through studs 12 and strips 9, to fingers 14: and thecopper strip 13. The rheostat is then short-circuited.

My invention is particularly applicable for starting motors, and therheostat shown is adapted for starting a three-phase inductionmotor, thethree leads from the secondary winding of the rotor being connected toterminals 11, and as the motor speeds up the resistance is graduallydecreased until it is entirely cut out. My invention is equally welladapted for general purposes, however, and one, two, three, or anynumber of terminals and plates may be used. In case one plate only isused one terminal would be connected to the plate and the other to thesheet-iron tank. I also wish it to be understood that I am not limitedto the exact construction shown and that various modifications may bedesigned and still be within the spirit of the claims.

I claim as my invention- 1. In a water-rheostat, the combination of areceptacle for the water, a hinged cover therefor, two or more platescarried by said cover, and means for shortcircuiting the plates when thecover is closed.

2. In a water-rheostat, the combination of a receptacle for the water, ahinged cover therefor, two or more plates carried by said cover,terminals connected to said plates, and means for short-circuiting theplates when the cover is closed.

3. In a water-rheostat, the combination of a receptacle for the water, ahinged cover therefor, two or more plates tapering in outline carried bysaid cover, terminals connected to said plates, and means forshort-circuiting the plates when the cover is closed.

4:- A water-rheostat including in combination a receptacle for thewater, a hinged cover therefor, conducting-plates secured to said cover.terminals connected to said plates, a conductor mounted on saidreceptacle, and conducting-strips connected to said plates which engagesaid conductor when the cover is closed.

5. A water-rheostat including in combination a receptacle for the water,a hinged cover therefor, conducting-strips and conductingplates securedto said cover, terminals connected to said plates, a conductor mountedon said receptacle, fingers connected to said conductor, said fingersbeing engaged by said conducting-strips when the cover is closed.

6. In a water-rheostat, the combination of a receptacle for the water, ahinged element, one or more conductors secured to said element andadapted to be immersed in the contents of the receptacle, and means forshortcircuiting the said conductor or conductors when the hinged elementis in one extreme position.

7 In a water-rheostat, the combination of a receptacle for the water, amovable element, one or more conductors secured to said element andadapted to be immersed in the contents of the receptacle, and meansoutside of the receptacle for .short-circuiting said conductor orconductors when said element is in one extreme position.

8. In a water-rheostat, the combination of a receptacle for the water, amovable element, one or more conductors secured to said element andadapted to be immersed in the contents of the receptacle, and meansoutside of the receptacle for short-circuiting said conductor orconductors when said element is in one extreme position.

9. In a water-rheostat, the combination of a receptacle for the water, ahinged element, one or more plates carried by said element, and meansfor short-circuiting the said plate or plates when the hinged element isin one extreme position.

In testimony whereof I affix my signature in presence of two witnesses.

\VILLIAM D. POMEROY. \Vitnesses:

L. K. SAGER, SANFORD KLEIN.

